294 



ELASMOBRANCHIL 

 PTYCHODUS, Agassiz. 



Pi)issou8 tbssiles, 18:i3, III, 150. 



Ptychodus polygyeus, Agassiz. 



■Poissons fossiles, III, p. 150 : Gibbcs, Jdunial of tbu Acadi'iny of Philadelphia, 1849, 299, 

 Plate XLII, figs. 5-6 ; Leidy, Proceedings of the Academy of Philadelphia, 1868, p. 208. 



Rotten limestone of Alabama, and Niobrara epoch of Kansas. 

 Ptychodus janevah, Cope. 



/Spoceforfiis jo»f!)oi). Cope, Hayden's BuUetiu of the United States Geological Survey of the 

 Territories, No. 2, 1874, p. 47. 



Niobrara Cretaceous of Kansas. 

 Ptychodus occidentalis, Leidy. 



Proceedings of the Academy of Philadelphia, 1868, p. '207 ; Report of the United St.ate8 Geo- 

 logical Survey of the Territories, 187;{, p. 398, Table XVII, 7-8, XVIII, 15-18. 



Niobrara epoch of the Smoky Hill. 

 Ptychodus mortonii, Agassiz. 



Poissons fossiles, 111, p. 158, Plate 25, figs. 1-3. 



Niobrara Cretaceous of the Smoky Hill River, Professor Mudge ; Ala- 

 bama ; Mississippi. 



Ptychodus whippleyi, Marcou. 



Geology of North America, 1858, p. 33 ; Leidy, Report, etc., 1873, 300, Table XVIII, 19-20. 



Niobrara epoch of the Arkansas River, Kaiistis ; also, Colorado and 

 Galisteo, New Mexico. Professor Merrill. 



Ptychodus mammili,aris, Agassiz. 



Poissons fossiles, III, p. 151. 



Cretaceous greensand, No. 4, of Delaware. 



Ptychodus papillosus, Cope. 



The grinders of this species possess the elevated form of those of P. 

 ivhi2)pleAji, and are of about the same size. The surface is characterized by 

 the absence of folds or ridges, but is uniformly covered with subequal areolae 

 or papilloB of small size, giving the cementum a shagreened appearance. 



Cretaceous, No. 3, of Colorado, east of the Rocky Mountains. 



